#include <linux/compiler.h>
#include <linux/kernel.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <string.h>

#include "data.h"
#include "util.h"
#include "debug.h"

static bool check_pipe(struct perf_data_file *file)
{
	struct stat st;
	bool is_pipe = false;
	int fd = perf_data_file__is_read(file) ?
		 STDIN_FILENO : STDOUT_FILENO;

	if (!file->path) {
		if (!fstat(fd, &st) && S_ISFIFO(st.st_mode))
			is_pipe = true;
	} else {
		if (!strcmp(file->path, "-"))
			is_pipe = true;
	}

	if (is_pipe)
		file->fd = fd;

	return file->is_pipe = is_pipe;
}

static int check_backup(struct perf_data_file *file)
{
	struct stat st;

	if (!stat(file->path, &st) && st.st_size) {
		/* TODO check errors properly */
		char oldname[PATH_MAX];
		snprintf(oldname, sizeof(oldname), "%s.old",
			 file->path);
		unlink(oldname);
		rename(file->path, oldname);
	}

	return 0;
}

static int open_file_read(struct perf_data_file *file)
{
	struct stat st;
	int fd;
	char sbuf[STRERR_BUFSIZE];

	fd = open(file->path, O_RDONLY);
	if (fd < 0) {
		int err = errno;

		pr_err("failed to open %s: %s", file->path,
			str_error_r(err, sbuf, sizeof(sbuf)));
		if (err == ENOENT && !strcmp(file->path, "perf.data"))
			pr_err("  (try 'perf record' first)");
		pr_err("\n");
		return -err;
	}

	if (fstat(fd, &st) < 0)
		goto out_close;

	if (!file->force && st.st_uid && (st.st_uid != geteuid())) {
		pr_err("File %s not owned by current user or root (use -f to override)\n",
		       file->path);
		goto out_close;
	}

	if (!st.st_size) {
		pr_info("zero-sized file (%s), nothing to do!\n",
			file->path);
		goto out_close;
	}

	file->size = st.st_size;
	return fd;

 out_close:
	close(fd);
	return -1;
}

static int open_file_write(struct perf_data_file *file)
{
	int fd;
	char sbuf[STRERR_BUFSIZE];

	if (check_backup(file))
		return -1;

	fd = open(file->path, O_CREAT|O_RDWR|O_TRUNC, S_IRUSR|S_IWUSR);

	if (fd < 0)
		pr_err("failed to open %s : %s\n", file->path,
			str_error_r(errno, sbuf, sizeof(sbuf)));

	return fd;
}

static int open_file(struct perf_data_file *file)
{
	int fd;

	fd = perf_data_file__is_read(file) ?
	     open_file_read(file) : open_file_write(file);

	file->fd = fd;
	return fd < 0 ? -1 : 0;
}

int perf_data_file__open(struct perf_data_file *file)
{
	if (check_pipe(file))
		return 0;

	if (!file->path)
		file->path = "perf.data";

	return open_file(file);
}

void perf_data_file__close(struct perf_data_file *file)
{
	close(file->fd);
}

ssize_t perf_data_file__write(struct perf_data_file *file,
			      void *buf, size_t size)
{
	return writen(file->fd, buf, size);
}

int perf_data_file__switch(struct perf_data_file *file,
			   const char *postfix,
			   size_t pos, bool at_exit)
{
	char *new_filepath;
	int ret;

	if (check_pipe(file))
		return -EINVAL;
	if (perf_data_file__is_read(file))
		return -EINVAL;

	if (asprintf(&new_filepath, "%s.%s", file->path, postfix) < 0)
		return -ENOMEM;

	/*
	 * Only fire a warning, don't return error, continue fill
	 * original file.
	 */
	if (rename(file->path, new_filepath))
		pr_warning("Failed to rename %s to %s\n", file->path, new_filepath);

	if (!at_exit) {
		close(file->fd);
		ret = perf_data_file__open(file);
		if (ret < 0)
			goto out;

		if (lseek(file->fd, pos, SEEK_SET) == (off_t)-1) {
			ret = -errno;
			pr_debug("Failed to lseek to %zu: %s",
				 pos, strerror(errno));
			goto out;
		}
	}
	ret = file->fd;
out:
	free(new_filepath);
	return ret;
}
dfba96c543e55b6672d5a37e'>perf</a>/<a href='/cgit.cgi/linux/net-next.git/commit/tools/perf/Documentation?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>Documentation</a>/<a href='/cgit.cgi/linux/net-next.git/commit/tools/perf/Documentation/jitdump-specification.txt?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>jitdump-specification.txt</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='h' value='nds-private-remove'/><input type='hidden' name='id' value='39cb2c9a316e77f6dfba96c543e55b6672d5a37e'/><table><tr><td colspan='2'/></tr><tr><td class='label'>context:</td><td class='ctrl'><select name='context' onchange='this.form.submit();'><option value='1'>1</option><option value='2'>2</option><option value='3' selected='selected'>3</option><option value='4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2017-01-29 13:50:06 -0800</td></tr>
<tr><th>committer</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2017-01-29 13:50:06 -0800</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/tools/perf/Documentation/jitdump-specification.txt?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>39cb2c9a316e77f6dfba96c543e55b6672d5a37e</a> (<a href='/cgit.cgi/linux/net-next.git/patch/tools/perf/Documentation/jitdump-specification.txt?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>98fe974ee4e20121253de7f61fc8d01bdb3821c1</a> /<a href='/cgit.cgi/linux/net-next.git/tree/tools/perf/Documentation/jitdump-specification.txt?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>tools/perf/Documentation/jitdump-specification.txt</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/tools/perf/Documentation/jitdump-specification.txt?h=nds-private-remove&amp;id=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>2c5d9555d6d937966d79d4c6529a5f7b9206e405</a> (<a href='/cgit.cgi/linux/net-next.git/diff/tools/perf/Documentation/jitdump-specification.txt?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e&amp;id2=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>diff</a>)</td></tr></table>
<div class='commit-subject'>drm/i915: Check for NULL i915_vma in intel_unpin_fb_obj()</div><div class='commit-msg'>I've seen this trigger twice now, where the i915_gem_object_to_ggtt()
call in intel_unpin_fb_obj() returns NULL, resulting in an oops
immediately afterwards as the (inlined) call to i915_vma_unpin_fence()
tries to dereference it.

It seems to be some race condition where the object is going away at
shutdown time, since both times happened when shutting down the X
server.  The call chains were different:

 - VT ioctl(KDSETMODE, KD_TEXT):

    intel_cleanup_plane_fb+0x5b/0xa0 [i915]
    drm_atomic_helper_cleanup_planes+0x6f/0x90 [drm_kms_helper]
    intel_atomic_commit_tail+0x749/0xfe0 [i915]
    intel_atomic_commit+0x3cb/0x4f0 [i915]
    drm_atomic_commit+0x4b/0x50 [drm]
    restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper]
    drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper]
    drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper]
    intel_fbdev_set_par+0x18/0x70 [i915]
    fb_set_var+0x236/0x460
    fbcon_blank+0x30f/0x350
    do_unblank_screen+0xd2/0x1a0
    vt_ioctl+0x507/0x12a0
    tty_ioctl+0x355/0xc30
    do_vfs_ioctl+0xa3/0x5e0
    SyS_ioctl+0x79/0x90
    entry_SYSCALL_64_fastpath+0x13/0x94

 - i915 unpin_work workqueue:

    intel_unpin_work_fn+0x58/0x140 [i915]
    process_one_work+0x1f1/0x480
    worker_thread+0x48/0x4d0
    kthread+0x101/0x140

and this patch purely papers over the issue by adding a NULL pointer
check and a WARN_ON_ONCE() to avoid the oops that would then generally
make the machine unresponsive.

Other callers of i915_gem_object_to_ggtt() seem to also check for the
returned pointer being NULL and warn about it, so this clearly has
happened before in other places.

[ Reported it originally to the i915 developers on Jan 8, applying the
  ugly workaround on my own now after triggering the problem for the
  second time with no feedback.

  This is likely to be the same bug reported as

     https://bugs.freedesktop.org/show_bug.cgi?id=98829
     https://bugs.freedesktop.org/show_bug.cgi?id=99134

  which has a patch for the underlying problem, but it hasn't gotten to
  me, so I'm applying the workaround. ]

Cc: Daniel Vetter &lt;daniel.vetter@intel.com&gt;
Cc: Jani Nikula &lt;jani.nikula@linux.intel.com&gt;
Cc: Ville Syrjälä &lt;ville.syrjala@linux.intel.com&gt;
Cc: Chris Wilson &lt;chris@chris-wilson.co.uk&gt;
Cc: Maarten Lankhorst &lt;maarten.lankhorst@linux.intel.com&gt;
Cc: Tvrtko Ursulin &lt;tvrtko.ursulin@intel.com&gt;
Cc: Imre Deak &lt;imre.deak@intel.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>Diffstat</a> (limited to 'tools/perf/Documentation/jitdump-specification.txt')</div><table summary='diffstat' class='diffstat'>